Achievements in unmanned and autonomous technology have enabled mobile platforms, such as, for example, land and sea vehicles, airborne vehicles, and space vehicles, to operate for indefinite periods of time. One limitation of such a mobile platform is its finite energy source. Many mobile platforms utilize an onboard fuel, such as, for example, a fossil fuel, fuel cell, or chemical battery, that is depleted over time of operation until the mobile platform is forced to refuel. At least some mobile platforms incorporate photovoltaic (PV) cells onto their skins, structures, or otherwise onboard the mobile platform to utilize as a direct energy source or to replenish an energy storage device, such as a chemical battery.
Incorporation of PV cells onto a mobile platform is an effective solution to extend time of operation, i.e., endurance, range, loiter, or time-on-station. However, a natural limitation of PV cells is their inability to harvest energy when sunlight is scarce or, in other words, at night. This limitation extends further to land and sea vehicles that may, from time to time, have to contend with weather conditions that diminish the availability of sunlight from which their onboard PV cells harvest energy; unlike aerial vehicles that avoid such conditions when operating at altitude, or above the cloud layer in the Earth's atmosphere. Similarly, space vehicles, such as satellites, often utilize PV cells to harvest energy from sunlight. However, even such space vehicles, from time to time, pass through the Earth's shadow.